Liquid cooling of power electronics is an evolving science. One sort of cooling device used today is formed by casting or machining, by an end mill, an open metal box having protrusions rising from the floor. This box is then closed by welding on a lid, and is turned upside down so that electrical components can be attached to a surface supported by the bottom of what had been the floor. One problem with this technique is that the casting and milling techniques used do not permit the formation of a dense array of thin protrusions, which is most effective at transferring heat into a passing liquid.
In another prior art method, sintered copper is molded into a form having narrow pins extending from a planar portion. These pins are, by necessity round. Moreover, this method is limited to the use of copper and appears to have had application only in air cooled assemblies. Copper is softer than is ideally desirable, and rather expensive. A method of making a fluid cooled assembly having thin (less than 3 mm) pins of a harder, stronger and less expensive material is desirable.